2018 Roadtrek with UHG

[larrylwill]

I have a 2018 Simplicity with UHG 280Amps. Since my house battery shorted and blew out my Inverter. I have installed 280W of Solar and a 280Amp Lifepo4 battery with 150A BMS, new ac switch new 10A Ac charger and a new 3000w Sine Wave inverter.

Since the BMS won't take the 280A from the UHG, I had to add a 60A DC to DC converter. On our last trip the UHG quit.

So now Im thinking why do I need the UHG? The standard Alternator is about 120A I think and it will be connected to the DC to DC and the starter battery. Why not just change the house battery over to the starter battery and add a separator so the Volkstart works?

I use the battery for a Coffie maker, 1 cup or Microwave or short time Air condition cool down. While running the engine. We mostly boondock.

What's the downside? Thanks.

[NeilConnect]

I am a very recent owner of a 2017 Roadtrek SS Agile. (No expert)
One point to consider is that the UHG is a "dual generator" so, the chassis and house are "separated".
Had your UHG been trouble-free up to this point?
Best of luck

[larrylwill]

yes, no problems, although the UHG has no Balmar so It has to be tickled to start it putting out. I was using a timer relay to apply house power 12v to the alternator output for 5 sec when starting..

[booster]

It sounds like a modified Roadtrek system that could have started as AGM or lithium. Both would have stand alone systems for coach and chassis. It would have had a Balmar remote regulator in it also. Has the Balmar been replaced with an internal regulator in the alternator?



Others will know better than I do, but I thought that the B to B chargers are generally capable of activating the alternator and that is very desirable to protect the parts of the system. Using the pulsed activation of the alternator from the starting system could be an issue with B to B being active and the alternator seeing a continuous battery in the system to prevent spikes from a closed output on a running alternator. I don't ever recall the need for separate activation of the alternator in either remote regulator or B to B systems.


That said, the Promaster probably has a 180 or 220 amp alternator in it. The Promaster has electric cooling fans that can pull probably up 40 amps and you have to allow for that, but the PCM controlled alternator should be able to turn down to save itself. I would guess the 220 amp alternator would do OK with the systems combined and pulling the about 80 amps it might take for the B to B charger and full output, but would close if the cooling fans and climate control fan and/or headlights were on.


The 280 amp alternators from that era can be repaired, sometimes reasonably and sometimes near the price of a new one. I just had one done for our van after poorly designed external regulator put full field on the non running alternator and fried it. Mine was totally toast and got all new internals and was within about $100 of the price of new. If you had a spike issue with yours that failed it, you would probably have lost the diodes in most cases. They have avalanche diodes which can handle some, but not all spikes.



A full system diagram would help so we can see how it is setup now and what components and models are used. Switching to combined may not be all that hard, or could be tougher depending on how it now and what else you would need.

[mumkin]

The Simplicity units that came with the UHG have an internal controller... no Balmar. They came with one AGM battery. A number of owners have done an upgrade to lithium, and it does take some tweaking. Our poster has appeared over on the Simplicity FB page, so he should find a few of them over there who can explain their process. (I think it has also been posted to their file section)

[larrylwill]

I ordered mine with volkstart and UHG. The UHG was hooked up to the house battery. When my original inverter/charger went out, I called Nations and they said it did not have a Balmar. So I replaced the house battery with 280A Lifepo4 battery, a 2000w inverter, a 110v AC switch, and 10A AC charger. I have 4 options that I know of. 1. I can pull the UHG and try to fix it. 2. I can send it back to Nations and pay them almost the price of a new one and still not have a Balmar. 3. I could replace it with a standard large alternator. 4. Charge the house battery off the starter alternator through the DC2DC converter. However, hooking up a lithium battery with a AGM is where people do not agree how. When I first did it I found the UHG put out more current than my BMS could handle and was advised to add the DC2DC which I did. But now there is no 12v hooked up to the UHG and it won't charge unless I put 12v on the output for a few seconds.

[booster]

Originally Posted by larrylwill

I ordered mine with volkstart and UHG. The UHG was hooked up to the house battery. When my original inverter/charger went out, I called Nations and they said it did not have a Balmar. So I replaced the house battery with 280A Lifepo4 battery, a 2000w inverter, a 110v AC switch, and 10A AC charger. I have 4 options that I know of. 1. I can pull the UHG and try to fix it. 2. I can send it back to Nations and pay them almost the price of a new one and still not have a Balmar. 3. I could replace it with a standard large alternator. 4. Charge the house battery off the starter alternator through the DC2DC converter. However, hooking up a lithium battery with a AGM is where people do not agree how. When I first did it I found the UHG put out more current than my BMS could handle and was advised to add the DC2DC which I did. But now there is no 12v hooked up to the UHG and it won't charge unless I put 12v on the output for a few seconds.

What B to B do you have? I think there should be sense wire that would go to the alternator to activate if it matches your system. You really want the coach battery to initiate the alternator so you can't have it running if the lithium pack goes off line and generates a big spike.



There is good reason to not hook up an AGM and lithium battery in parallel. I tested such a system on small scale and it doesn't work unless you can disconnect them from each other for both charging and discharging. While the charge voltages are similar at the high end, the current split is extreme and to get the AGM full takes many hours to do, and that will overcharge the lithium battery at high voltage.


Resting voltage is much different for AGM and lithium and as soon as the charging goes off, the lithium is going to be running everything and charging the AGM so could overpower your 150 amp BMS for the lithium.


In our system I don't activate the second alternator off the ignition as such, but I do power it from there. I also have a coach battery voltage sense that will not let it charge without the coach lithium batteries online. I am using a Wakespeed remote regulator with no B to B on it and charge at 120 amps (regulator controlled). It also softstarts the regulator, as does a Balmar, so it doesn't get that huge hit at startup that putting 12v on the field will do, causing the output to spike.

[larrylwill]

My DC2DC is a Renology 60A. The last idea I got was to just connect the DC2DC to the starter AGM and alternator and let the B2B be used as a isolator. Sounds too simple.

Alternator &
Starter Battery
|
DC2DC converter
|
House Lithium Batteries

[booster]

Originally Posted by larrylwill

My DC2DC is a Renology 60A. The last idea I got was to just connect the DC2DC to the starter AGM and alternator and let the B2B be used as a isolator. Sounds too simple.

Alternator----0-----Starter Batt.
|
|
DC2DC
|
House Lithium Batteries

Oh, so you don't have an AGM and lithium with parallel charging. The B to B isolates them so there is no issue with that if you connect them together. The AGM starter is charged by the chassis alternator directly and if you connect the chassis alternator to the B to B it will handle the lithium separately. Lots and lots of systems like that being used now.

[larrylwill]

The lithium's are charged through the DC2DC from the UHG. The Starter AGM is charged from the starter alternator directly. If I just have to connect the AGM battery to the DC2DC, that would be the simplest.
Thank you

[larrylwill]

Done, and it works
thanks